"An easie way to procure Fire speedily. Take a round Glasse, and fill it with faire water, and set it against the Sun, so that it may stand fast: then take something that is very dry and hold it neere the Glasse (betweene the glasse and the Sun) and it will set the thing so holden on fire: which is very strange to behold, the rather, because Fire which is an hot and dry Element, is procured out of Water, which is a cold and moist Element."
The Booke of Pretty Conceits (1628)This is a great trick if you can get the angle just right. If not, though, you'll still end up with a nice glass of lukewarm water. Win!